In the progression of semiconductor device miniaturization, there is a desire to form a fine pattern that is smaller than the resolution limit of lithography using an aligner or stepper. As a method of realizing this miniaturization, a so-called sidewall transfer process is known, where a sidewall film (spacer film) is formed on the sidewalls of a feature in the core film formed by lithographic techniques, and the core film is removed to leave the sidewall film that is used as a mask in order to process the underlying layer.
According to this method, a line and space pattern with a half pitch of the pitch limit of the lithography resolution can be formed. Further repetition of the sidewall transfer process enables a line and space pattern with a further finer pitch such as ¼ and ⅛ of the pitch limit of the lithography resolution.
However, in the process of forming such a sidewall film mask, to process a wafer to form the sidewall mask, the wafer must be moved among a plurality of independent devices, such as a film formation device, for conformably forming a sidewall film on the exposed surface of the core film, a dry etching device for performing a dry etch process on the thin film layer to etch back the sidewall film on the top surface of the core film to eliminate the same, and a wet etching device for removing the core film. Therefore, the process of forming a sidewall film mask becomes complicated and is costly.